Autoinjector Shroud Locking Mechanism for Safety
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Solution Overview
Problem
Existing autoinjector devices lack a reliable mechanism to prevent accidental or premature release of the shroud and syringe carrier, particularly during impacts or before use, which can lead to safety issues.
Innovation Solution
A locking arrangement between the shroud and latch is introduced, which must be unlocked by movement of the shroud, featuring a retention feature on the body portion and a biased shroud deployment spring, allowing the shroud to automatically move from a retracted to an extended position after firing and lock in place, preventing premature release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking arrangement is introduced between the shroud and latch to prevent accidental release, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The locking arrangement is implemented by nesting the latch element within the shroud structure, where the latch element engages with a retention feature on the syringe carrier through a slot in the shroud. This nested configuration provides reliable locking without requiring separate external locking components, thus improving safety while minimizing additional complexity.
Solution Approach 2:
The locking mechanism is designed to be self-actuating through the biased shroud deployment spring. The spring automatically urges the shroud from retracted to extended position after injection, and the latch element automatically engages with the retention feature without requiring user intervention. This self-service mechanism enhances reliability while avoiding the complexity of manually operated locking systems.
2Reliability
If the shroud is designed to automatically move to extended position after firing, then safety is improved, but control over shroud movement timing becomes more complex
Solution Approach 1:
The shroud deployment spring is pre-loaded during device assembly to store elastic potential energy. This preliminary action prepares the spring to automatically urge the shroud to the extended position after injection, ensuring safety without requiring complex active control systems. The spring's pre-stored energy drives the shroud movement at the appropriate time based on the injection sequence.
Solution Approach 2:
The shroud is designed with dynamic movement capability through the slot and latch element arrangement, allowing it to transition from a fixed retracted position to an extended position. The biased spring provides continuous force to move the shroud dynamically after firing, achieving automatic safety deployment while maintaining simplicity through passive mechanical dynamics rather than active control.
3Ease of operation
If the latch element is allowed to deflect to release the syringe carrier, then ease of operation is improved, but reliability may be compromised due to potential premature release
Solution Approach 1:
The locking arrangement with the latch element and retention feature creates a preliminary anti-action that prevents premature release of the syringe carrier. The latch element must be deliberately deflected to disengage from the retention feature, and the locking geometry ensures that accidental forces during normal operation or impact cannot cause premature release. This preliminary protective action maintains reliability while allowing intentional release when needed.
Solution Approach 2:
The resilient nature of the latch element provides beforehand cushioning against accidental release. The element's elasticity allows it to absorb minor impacts or forces without deflecting enough to disengage from the retention feature, while still permitting deliberate release when properly actuated. This cushioning effect protects against premature release while maintaining ease of intentional operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The locking arrangement effectively prevents accidental or premature release of the shroud and syringe carrier, enhancing safety by ensuring the shroud only moves to its extended position after injection is complete and the device is removed from the injection site, thus reducing the risk of needle stick injuries.
Implementation Method 1
a biased shroud deployment spring, allowing the shroud to automatically move from a retracted to an extended position after firing
Data Source
Figure 1
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Figure 3(A)
AI summary
An autoinjector device is disclosed which comprises a body portion and a syringe carrier, for supporting a syringe with a needle at its forward end. The syringe carrier is moveably mounted within the housing such that forward movement relative to the housing may extend the needle from a forward end of the body. The syringe carrier has a latch element arranged to cooperate with a corresponding retention feature of the body portion to releasably hold the syringe carrier in a rearward position within the body potion. A delivery mechanism is arranged to forwardly displace the syringe carrier relative to the housing and to deliver a dose of medicament from the syringe. A shroud assembly is provided at a forward end of the device. The shroud further comprises a locking arrangement which blocks releasing movement of the latch element from the retention feature when the shroud is in a first, forward position and is unlocked when the shroud is in a second, rearward position.